To examine the effect of changing levels of support during NAVA-ventilation ("NAVA-level") on electrical diaphragm activity of the newborn on invasive or non-invasive NAVA ventilation.

The aim is to explore whether a so-called 'breakpoint', as defined in previous studies on NAVA ventilation in adults and children(1, 9), can be determined in newborn infants. Knowledge of this breakpoint will be used to optimise the settings of NAVA level at initiation of invasive or non-invasive NAVA ventilation.

This is an explorative study conducted in preparation of a randomized controlled trial that is planned in the near future to compare the effects of non-invasive NAVA with nasal continuous positive airway pressure (CPAP) in newborn infants.

Inclusion Criteria:

• Newborns admitted to the NICU in need for respiratory support and put on invasive or non-invasive NAVA by the attending physician. Patients will be included when they are clinically stable and within 24h after starting NAVA or nivNAVA.

Exclusion Criteria:

• - Congenital malformations of the diaphragm or respiratory system, including congenital diaphragmatic hernia.
• Patients with abnormalities of the upper airway (e.g. vocal cord paralysis, post-extubation laryngeal edema, Pierre-Robin sequence…).
• More than 20% of time spent in back-up ventilationWhen a patient on NAVA ventilation is apneic for a certain period of time (apnea time), the ventilator switches tot backup-ventilation. Backup-ventilation is pressure controlled, the apnea time can variate between 2 and 10 seconds.
• Clinically unstable patients:
• hemodynamic instability as defined by need of inotropic support or
• rapid respiratory deterioration on NAVA ventilation.
• No informed consent.